A well-known tandem color laser printer includes a plurality of photosensitive drums each corresponding to one of four colors of yellow, magenta, cyan and black, and a plurality of developing cartridges for supplying toner of respective colors to the corresponding photosensitive drums.
Such conventional developing cartridges are detachably mountable on a drawer unit that integrally supports the plurality of photosensitive drums. Each developing cartridge accommodates toner therein and includes a developing roller and a supply roller.